In industry known the method of measuring of uneven motion of a fluid (RU 2140538, E21B47/10, G01F1/66 (JSC “Tatneft”), 27.10.1999). The object of the invention is to simplify the process control flow of the fluid flowing through the pipeline. The method comprises measuring the time the liquid passing through a pipe with known size, the speed of the transmission and subsequent processing the data. The new is—the time the liquid passing the pipe section with known size is determined by the presence of acoustic noise generated by the motion of the fluid, and the rate of passage of the liquid is determined by the frequency of occurrence of portions of the acoustic noise caused by non-uniformity of fluid motion.
The disadvantage of the known methods is the lack of analysis of acoustic signal data, such as frequency and amplitude. The acoustic signal is used only to determine the total fluid velocity without recognizing the individual phases, and determining the beginning and end of the fluid flow.
Also known the method for measuring the flow of multiphase fluids (“The oil and gas wells operational control system” the magazine “Modern automation technology>> No. 2, 2001, p. 44-49), in which the flow rate is measured by the amplitude of the spectral power changes in pressure in the pipeline after setting in line narrowing device of the special form (whistle), effective to measure the flow with high GOR.
The disadvantage of the method is—the method applicable for gas wells with low liquid phase in the flow only.
In the oil-water emulsions with a low gas-oil ratio the method is not applicable because the liquid block the orifice. In other words, “whistle” in the fluid will not generate the signal. The method does not require to measure the physical properties of the liquid phase, for example sound speed. In case of presence of the sand in the flow the orifice nozzle deteriorates and it leads to the inaccurate flow measurement.
The method for measuring multiphase fluid flow (U.S. Pat. No. 7,401,530 B2 on Jul. 22, 2008 “SONAR BASED MULTIPHASE FLOWMETER”) was chosen as the prototype. In this method measures the speed of sound in the individual phases of the multiphase fluid moving in the pipe, measure the speed of wave spreading along the pipe, measure the volume of one phase of the flow, measured average velocity of the multiphase fluid in the pipe, measured density of each phase, and then, based on the proposed algorithm is calculated volume or mass flow of each phase. In this case, the speed of sound is used only as a mark to recognize the particular phase in the pipe, assuming that the velocity changes because of the flow phases ration is known in advance. The disadvantages of the prototype are:
1. Use equipment to measure the only one phase in a multiphase flow, for example, water, leads to additional errors in flow measurement. The errors occur because the phase ratio at the multi-phase flow varied significantly.
2. The presents of the hydrophilic and hydrophobic phases in the flow leads to deposits on the pipe walls. The deposits adversely affecting the measurement process of one of the phases. This applies to all type sensors—magnetic, electric, radiant, ionizing (see. p. 6-9 of the patent).
3. The mathematical correlation between the flow velocities, the particular phase velocity and densities of the phases is not given in the description.
4. Use two separate flowmeter to measure the multiphase flow and water flow as proposed in the method is not required. All essential information can be obtained from the acoustic sensor installed at the pipe.